Drug-coated microneedles for rapid and painless local anesthesia

• Published in: Biomedical microdevices 2017-03, Vol.19 (1), p.2-11, Article 2
• Main Authors: Baek, Sung-Hyun, Shin, Ju-Hyung, Kim, Yeu-Chun
• Format: Article
• Language: English
• Subjects: Administration, Topical; Anesthesia; Anesthetics; Anesthetics, Local - administration & dosage; Anesthetics, Local - metabolism; Animals; Arrays; Biological and Medical Physics; Biomedical Engineering and Bioengineering; Biophysics; Coating; Drug Delivery Systems - instrumentation; Drug Liberation; Drug therapy; Efficiency; Engineering; Engineering Fluid Dynamics; In vitro testing; Lidocaine - administration & dosage; Lidocaine - metabolism; Microtechnology - instrumentation; Nanotechnology; Needles; Pain - prevention & control; Pain management; Penetration; Permeability; Polyesters; Skin - metabolism; Swine; Time Factors
• ISSN: 1387-2176; 1572-8781
• DOI: 10.1007/s10544-016-0144-1

This study showed that drug-coated PLLA (Poly (L-lactide)) microneedle arrays can induce rapid and painless local anesthesia. Microneedle arrays were fabricated using a micro-molding technique, and the needle tips were coated with 290.6 ± 45.9 μg of lidocaine, the most widely used local anesthetic worldwide. A dip-coating device was newly designed for the coating step using an optimized coating formulation. Lidocaine coated on the arrays was released rapidly into PBS within 2 min, and its stability in storage lasted 3 weeks at 4, 25, and 37°C. Furthermore, the microneedle arrays showed consistent in vitro skin penetration and delivered 200.8 ± 43.9, 224.2 ± 39.3, and 244.1 ± 19.6 μg of lidocaine into the skin 1, 2, and 5 min after application with a high delivery efficiency of 69, 77, and 84%. Compared to a commercially available topical anesthetic EMLA® cream, a 22.0, 13.6, and 14.0-fold higher amount of lidocaine was delivered into the skin. Note, in vitro skin permeation of Lidocaine was also notably enhanced by a 2-min-application of the lidocaine-coated microneedle arrays. Altogether, these results suggest that the biocompatible lidocaine-coated PLLA microneedle arrays could provide significantly rapid local anesthesia in a painless manner without any of the issues from topical applications or hypodermic injections of local anesthetics.